Process for preparing polyhalo phenols

ABSTRACT

A process is provided for the hydrolysis of polyhalobenzenes to polyhalophenols in good yields and purity by initially reacting ethylene glycol with an alkali metal hydroxide to obtain a mixture comprising ethylene glycol alkali metal derivative, alkali metal hydroxide and ethylene glycol, adding to the latter mixture a mono- or di-alkylated benzene, such as toluene or ethylbenzene, then introducing a polyhalobenzene, whereby hydrolysis of the latter occurs and, thereafter, recovering the hydrolyzed benzene.

United States Patent Michaels et al. May 30, 197 2 [541 PROCESS FOR PREPARING 2,803,670 8/1957 Galat ..260/623 POLYHALO PHENOLS Primary Examiner-Bernard Helfin [72] Inventors: Edwin B. Mlchaels, Gregory Court, Nor- Assistant 3 Lone walk, Conn 06855; John W. Lee, Glen Avenue, Norwalk, Conn. 06850 [22] Filed: July 31, 1968 [2]] App]. No.2 748,981

[52] US. Cl. ..260/623 R [5 1 Int. Cl. ..C07t 39/32 [5 8] Field of Search ..260/623, 623 R, 629

[56] References Cited UNITED STATES PATENTS 2,509,245 5/1950 Nikawitz ..260/623 Attorney-Kenneth S. Goldfarb ABSTRACT A process is provided for the hydrolysis of polyhalobenzenes to polyhalophenols in good yields and purity by initially reacting ethylene glycol with an alkali metal hydroxide to obtain a mixture comprising ethylene glycol alkali metal derivative, alkali metal hydroxide and ethylene glycol, adding to the latter mixture a monoor di-alkylated benzene, such as toluene or ethylbenzene, then introducing a polyhalobenzene, whereby hydrolysis of the latter occurs and, thereafter, recovering the hydrolyzed benzene.

10 Claims, No Drawings PROCESS FOR PREPARING POLYHALO PHENOLS The present invention relates to the manufacture of polyhalophenols as well as to the corresponding alkali metal phenates of the same. More particularly, it relates to the manufacture of a trichlorophenol by the hydrolysis of a tetrachlorobenzene utilizing a hydrolysis mixture comprising ethylene glycol alkali metal derivative, a monoor di-alkylated benzene and with attendant recovery of trichlorophenols in good yields and purity. Still more particularly, the invention is concerned with the manufacture of a trichlorophenol of at least 99 percent purity with attendant high yields of ethylene glycol recovery by utilizing a plurality of operations commencing with a hydrolysis mixture comprising (a) an ethylene glycol alkali metal derivative, ethylene glycol and alkali metal hydroxide, and (b) a monoor di-alkylated benzene, then adding a tetrachlorobenzene thereto, effecting hydrolysis and adjusting the alkalinity of the resultant hydrolyzed mixture to a pH between 11 and 13, incorporating a high boiling higher alkane such as those containing from 16 to 24 carbon atoms, whereby ethylene glycol is recovered by distillation and, thereafter, advantageously recovering trichlorophenols from the corresponding alkali metal phenate solution.

As is known, chlorinated benzenes and, particularly l,2,4,5- tetrachlorobenzene, can be hydrolyzed by diverse methods, each of which is not wholly satisfactory with respect to overall yield and purity. For instance, the hydrolysis of chlorinated benzenes proceeds with great difficulty using caustic soda except under extremely high temperatures and pressures. To overcome such rigorous conditions, sundry alcohols, as for example methanol or ethylene glycol, have been employed in an hydrolysis mixture so as to control the rate of halobenzene hydrolysis, whereby only a single hydroxyl group appears on the benzene moiety. However, the use of the methanol is not satisfactory, since the formation of ether type derivatives, such as anisoles, occurs and the latter cannot be removed readily from the so-formed halophenol, thereby reducing markedly the purity of the resultant phenol. The use of glycols has also been found to be unsatisfactory, due to the presence of large excesses of water formed during the formation of ethylene glycol alkali metal derivative with a base. In practice, the hydrolysis reaction is difficult to perform and, therefore, has been markedly restricted, due to the inhibiting action of water, unless all the water is removed prior to hydrolysis by means of an inert entraining agent. However, the entrainment of water results in the formation of large amounts of difficultto-remove by-products. In addition, the use of glycol involves the steps of either distilling the same directly from the reaction mixture which will result in degradation of the hydrolyzed polyhalobenzene or efiecting acidification, followed by water washing to recover the glycol from the water by a series of troublesome, costly fractionations. If a method could be provided to overcome the foregoing difficulties, it would serve to fulfill a long-felt need in the art.

It is, therefore, a principal object of the invention to provide economical hydrolysis process for converting polyhalobenzenes to alkali metal polyhalophenates and to the corresponding polyhalophenols utilizing a menstruum containing (a) free alkali metal hydroxide, free ethylene glycol and ethylene glycol alkali metal derivative and (b) a monoor di-alkylated benzene, whereby high yields usually ranging from 88 to 92 percent and high purity, usually not less than 99 percent, of polyhalophenols are obtained. It is a further object of the invention to provide an economical method for the recovery of ethylene glycol from a hereinabove defined hydrolyzed mixture or equivalent mixtures utilizing a higher boiling alkane. It is a still further object of the invention to recover by distillation a pure halogenated phenol from a crude material by admixing ammonia or ammonium hydroxide thereto. Other objects and advantages will become apparent from a reading of the ensuing description.

According to the process of the invention, high yields of polyhalophenols and, particularly trichlorophenols, of more than 85 percent of theory in purities of 99 percent, or higher,

have been surprisingly prepared in essentially a three step operation. These critical steps involve the initial reaction of ethylene glycol with an alkali metal hydroxide with resultant formation of a mixture of alkali metal hydroxide, ethylene glycol and ethylene glycol alkali metal derivative and in a second step incorporating into said mixture a small amount of hydrolysis controlling reagent comprising a monoor di-alkylated benzene. To the latter is then added in a third step a polyhalogenated benzene and particularly tetrachloro benzene. Unexpectedly, high yields of desired alkali metal polyhalogenated phenates and the corresponding polyhalogenated phenols are obtained in good yield and purity.

In general, the hydrolysis mixture can advantageously be prepared by reacting from 4 to 8 mols of ethylene glycol, and preferably from 5 to 6.5 mols of ethylene glycol, and from about 2.2 to about 3 mols of an alkali metal hydroxide, such as sodium hydroxide, potassium hydroxide or lithium hydroxide until from 1 to 2 mols of water are removed from the mixture. If more than 2 mols of water are removed, the amount in excess of 2 mols is then re-introduced into resultant mixture. There is then provided a mixture of from 1 to 2 mols of ethylene glycol alkali metal derivative, from 0.2 to 2 mols of free alkali metal hydroxide and from 2 to 7 mols of free ethylene glycol. The reaction in which there is formed the desired mixture is advantageously carried out under pressures ranging from mm Hg to atmospheric at temperatures between about C. and about 210 C. However, with the continuous evolution of water beyond the 2 mols of water by entrainment or the use of other means to form the glycol alkali metal derivative, there is obtained a hydrolysis mixture in which no free alkali metal hydroxide or free glycol is found. Where the latter mixture is employed, there is noted marked losses in yield and purity of hydrolyzed polyhalobenzene due to the formation of undesirable condensation reactions.

To the above pre-reacted ethylene glycol hydrolysis mixture is then added a hydrolysis controlling agent, namely, a monoor di-alkylated benzene containing of from 1 to 4 carbon atoms in the alkyl substituent. The amount incorporated ranges advantageously from about 0.05 mol to about 0.25 mol per mol of the tetrahalobenzene to be hydrolyzed. Exemplary of the monoor di-alkyl benzenes which can be employed as the hydrolysis controlling reagent are: toluene, xylene, o-ethyl benzene, n-propyl benzene, o-isobutyl butylbenzene, 1,4- diethyl benzene, 1,4-di-isopropyl benzene, l-ethyl-4-n-propyl benzene as well as isomers of the same. Absent the added hydrolysis controlling reagent, the resultant hydrolysis is uncontrollable, resulting in a tarry mass.

Illustrative of the polyhalobenzenes to be treated by the soformed hydrolysis mixture are: l,2,4,5-tetrachlorobenzene, l,2,3,5-tetrachlorobenzene, or l,2,4-trichlorobenzene, or l,2,4-tribromobenzene, or pentachlorobenzene. Advantageously, the time to effect the hydrolysis ranges from l to 3 hours at reflux temperatures usually in the range of from about to 200 C. The pH of the resultant hydrolyzed mixture is 14. The latter mixture can, if desired, be next acidified with any inert acid, such as hydrochloric acid or sulfuric acid, to reduce the pH from 14 to about 11 to 13 and, preferably from 12 to 12.5. There is next added thereto an alkane of from 16 to 24 carbon atoms such as hexadecane, heptadecane, eicosane, mineral oils or paraffin in amounts ranging from 10 to 60 grams per mol of polyhalobenzene and, particularly, the tetrahalobenzene employed. This addition is critical, because otherwise purity of product of hydrolyzed polyhalobenzene is not realized due to formation of side reactions and substantial loss of resultant corresponding alkali metal phenate and glycol is experienced. Water and the hydrolysis controlling reagent are initially removed and recovery of ethylene glycol is next achieved without any reduction in overall yield of desired final product which, for instance, can be trichlorophenol. To recover the latter, there is utilized vacuum distillation at pressures ranging from about 8 to 10 mm Hg pressure. The glycol distillate is then recovered.

Resultant residue is admixed with sufiicient water to dissolve the alkali metal phenate formed during hydrolysis. The water layer is next separated from any residual, water-insoluable organic substance. To the water layer is added sufficient acid, such as sulfuric acid, to further reduce the pH of the mixture to from 4 -4.5, whereby the recovered alkali metal henate is converted to the corresponding halogenated phenol. Two layers form again. The upper water layer is discarded, but the lower layer containing the phenol is washed several times with water at temperatures ranging from about 65 to 100 C. To insure purity of latter product, there is admixed miniscule amounts of ammonia or ammonium hydroxide, usually in the range of from about 1 to 5 cc, to the recovered phenol. The latter mixture is dehydrated and flash distilled at from 1 to 5 mm Hg pressure to recover at least 99 percent pure halogenated phenol in yields ranging from about 89 to about 92 percent of theory. Advantageously, the utilization of ammonia of ammonium hydroxide is applicable to the purification and recovery of any halogenated phenol prior to vacuum distilling the latter crude phenol.

The following examples are presented as merely illustrative and are not to be taken as being limitative of the invention. Unless otherwise stated, any parts given are by weight.

EXAMPLE 1 To a stainless steel reaction vessel equipped for vacuum distillation are added 2.5 mols of sodium hydroxide and 6.0 mols of ethylene glycol and heated to a temperature of 160 C. under a vacuum of 150 mm Hg to remove mols of water. Thereafter, 0.1 l mol of xylol is added to the mixture comprising ethylene glycol sodium derivative, free ethylene glycol and free sodium hydroxide. To the latter are added 1.0 mol of 1,2,4,5-tetrachlorobenzene. The temperature which has dropped to 140 C. is gradually raised to 180 C. and maintained for 2 hours under gentle reflux in which no water or solvent are lost to the atmosphere. The hydrolysis reaction is completed when there is an absence of tetrachlorobenzene is the reaction mixture. There is then recovered a mixture containing sodium 2,4,5-trichlorophenate.

Substituting l-ethyl-4-propylbenzene for xylol and potassium hydroxide for sodium hydroxide, there is recovered potassium 2,4,5-trichlorophenate.

EXAMPLE 2 The resultant mixture of Example 1 containing sodium 2,4,5-trichlorophenate is treated to recover glycol therefrom by neutralizing excess alkali. This is accomplished by adding 24 grams of 66 percent sulfuric acid so as to reduce the pH from 14 to a pH of 12.5. Twenty grams of paraffin having a melting point of 135 F. are next added to the so-acidified mixture and placed under 150 mm Hg to flash over xylol and traces of water. Ethylene glycol (4.2 mols) is next distilled off and recovered.

Residual sodium 2,4,5-trichlorophenate and parafiin are then diluted with 250 cc water. The latter phenate dissolves in the water and the paraffin is separated from the phenate solution.

To the latter phenate solution is next added 96 grams of 66 percent sulfuric acid to convert the phenate to the corresponding 2,4,5-trichlorophenol at a pH of about 4.0 which separates at between 60 C. and 80 C. as an oily layer and is washed with hot water to remove free acid. The crude phenol at this point is recovered in a yield of 190 grams having a crystallizing point of 54 C.

To the crude phenol is added 3 milliliters of concentrated ammonium hydroxide. The latter effectively neutralizes any entrained acids and forms miniscule amount of the corresponding ammonium phenate which decomposes under conditions of distillation. The presence of small amounts of ammonium phenates prevents decomposition of the phenol due to avoidance of either excess alkali or acid during the distillation procedure.

Resultant 2,4,5-trichlorophenol is dehydrated and flashed distilled under vacuum and there is collected 176 grams of 2,4,5-trichlorophenol equivalent to a percent yield and having a crystallizing point of 635 C.

EXAIVIPLE 3 The procedure of Example 2 above is repeated in every respect except that xylol is omitted an an hydrolysis controlling reagent additive. There results a tarry mass with an attendant uncontrollable hydrolysis reaction with temperatures rising to as high as 250 C.

Example 4 Repeating Example 2 in every detail except that 1.5 mols of sodium metal under nitrogen molten and 6 mols of ethylene glycol in which one mol of sodium hydroxide has been previously dissolved are substituted for the sodium hydroxide and ethylene glycol to also yield free sodium hydroxide, free ethylene glycol and ethylene glycol monosodium derivative.

Similar overall yields and purities as shown in Example 2 of 99.1 percent purity and 91 percent yields of 2,4,5- trichlorophenol are attained.

EXAMPLE 5 Repeating the procedure of Example 2 in every detail except that in the pre-reaction step prior to hydrolysis 2 mols of water are withdrawn and collected and 0.6 mol of toluene is employed as the hydrolysis controlling reagent for an overall reaction time of 1 hour at 175 C., there is ultimately recovered 179 grams of 2,4,5-trichlorophenol having a crystallizing point of about 64.0 C.

EXAMPLE 6 The procedure of Example 2 is repeated in every detail except that 0.058 mol of ethyl benzene is substituted for the xylol of Example 2 with attendant overall 90 percent yields of 2,4,5-trichlorophenol having a crystallizing point of 64 C. and a purity of 99.2 percent.

EXAMPLE7 Repeating Example 2 in every detail except pentachlorobenzene is substituted for 1 ,2,4,5-

tetrachlorobenzene, and mineral oil is substituted for mineral spirits, there is obtained good overall yields of 2,3,5,6- tetrachlorophenol.

Similarly, either 1,2,4-trichlorobenzene or 1,2,4- tribromobenzene is hydrolyzed as in the above example to obtain high yields and purity of 2,5-dichlorophenol, or 2,5-dibromophenol, respectively.

We claim;

1. In a process for preparing polychlorophenols or polybromophenols from polychlorobenzenes or polybromobenzenes by subjecting the latter to hydrolysis utilizing alkaline ethylene glycol, the improvement which comprises the steps of:

a. admixing in the absence of a water-entraining agent of from 4 to 8 mols of ethylene glycol with from 2.2 to 3 mols of an alkali metal hydroxide,

. heating the mixture to a temperature from to about 210 C., under reduced or atmospheric pressure and removing from the resultant mixture 1 to 2 mols of water thereby forming from 1 to 2 mols of ethylene glycol alkali metal derivative, from 0.2 to 2 mols of free alkali metal hydroxide and from 2 to 7 mols of free ethylene glycol,

c. incorporating into the resultant mixture of (b) above from about 0.05 mol to about 0.25 mol of a mono (lower) 1 to 4 C alkyl benzene or a di (lower) 1 4 C alkyl benzene hydrolysis controlling reagent per mol of polyhalobenzene to be hydrolyzed to form a hydrolysis mixture, and

d. hydrolyzing a polyhalobenzene in said hydrolysis mixture.

e. acidifying the resultant hydrolyzed mixture to a pH of between 11 and 13 2. A process according to claim 1 in which the polyhalobenzene is 1,2,4,5-tetrachlorobenzene.

3. A process according to claim 1 for preparing 2,4,5- trichlorophenol from 1,2,4,5-tetrachlorobenzene by subjecting the latter to hydrolysis utilizing alkaline ethylene glycol, the improvement which comprises:

a. admixing in the absence of a water-entraining agent of from 4 to 8 mols of ethylene glycol with from 2.2 mols to 3 mols of an alkali metal hydroxide,

b. heating the mixture to a temperature from 150 to about 210 C., under reduced or atmospheric pressure and removing from the resultant mixture 1 to 2 mols of water thereby forming from 1 to 2 mols of ethylene glycol alkali metal derivative, from 0.2 to 2 mols of free alkali metal hydroxide and from 2 to 7 mols of free ethylene glycol,

c. incorporating into the resultant mixture of (b) above from 0.05 to 0.25 mol of a mono- (lower) 1 to 4 C alkyl benzene or a di- (lower) 1 to 4 C alkyl benzene hydrolysis controlling reagent per mol of tetrachlorobenzene to be hydrolyzed to form a hydrolysis mixture,

d. incorporating 1 mol of 1,2,4,5-tetrachlorobenzene into said hydrolysis mixture,

e. hydrolyzing resultant mixture at reflux temperatures ranging from about 170 to about 200 C., and

f. recovering said hydrolyzed tetrachlorobenzene,

4. A process according to claim 3 for preparing 2,4,5- trichlorophenol from l,2,4,5-tetrachlorobenzene by subjecting the latter to hydrolysis utilizing alkaline ethylene glycol, the improvement which comprises:

a. admixing in the absence of a water-entraining agent of from 4 to 8 mols of ethylene glycol with from 2.2 mols to 3 mols of an alkali metal hydroxide,

b. heating the mixture to a temperature from 150 to about 210 C., under reduced or atmospheric pressure and removing from the resultant mixture 1 to 2 mols of water thereby forming from 1 to 2 mols of ethylene glycol alkali metal derivative, from 0.2 to 2 mols of free alkali metal hydroxide and from 2 to 7 mols of free ethylene glycol,

c. incorporating into the resultant mixture of (b) above from 0.05 to 0.25 mol of a mono- (lower) 1 to 4 C alkyl benzene or a di- (lower) 1 to 4 C alkyl benzene hydrolysis controlling reagent per mol of tetrachlorobenzene to be hydrolyzed to form a hydrolysis mixture,

incorporating 1 mol of l,2,4,5-tetrachlorobenzene into said hydrolysis mixture,

e. hydrolyzing resultant mixture at reflux temperatures ranging from about 170 to about 200 C.,

f. acidifying the resultant hydrolyzed mixture to a pH of between 11 and 13,

g. incorporating in the so-acidifled mixture of (f) an alkane of from 16 to 24 carbon atoms in amounts ranging from about to 60 grams per mol of said tetrachlorobenzene, and

h. distilling the latter mixture to remove therefrom ethylene glycol.

5. A process according to claim 3 for preparing 2,4,5- trichlorophenol from 1,2,4,5-tetrachlorobenzene by subjecting the latter to hydrolysis utilizing alkaline ethylene glycol, the improvement which comprises:

a. admixing in the absence of a water-entraining agent of from 4 to 8 mols of ethylene glycol with from 2.2 mols to 3 mols of an alkali metal hydroxide,

b. heating the mixture to a temperature from 150 to about 210 C., under reduced or atmospheric pressure and removing from the resultant mixture 1 to 2 mols of water thereby forming from 1 to 2 mols of ethylene glycol alkali metal derivative, from 0.2 to 2 mols of free alkali metal hydroxide and from 2 to 7 mols of free ethylene glycol,

c. incorporating into the resultant mixture of (b) above from 0.5 to 0.25 mol of a mono- (lower) 1 to 4 C alkyl benzene or a di- (lower) 1 to 4 C alkyl benzene hydrolysis controlling reagent per mol of tetrachlorobenzene to be hydrolyzed to form a hydrolysis mixture,

. incorporating one mol of 1,2,4,5-tetrachlorobenzene into said hydrolysis mixture,

. hydrolyzing resultant mixture at reflux temperatures ranging from about 170 to about 200 C.,

. acidifying the resultant hydrolyzed mixture to a pH of between 11 and 13,

g. incorporating in the so-acidified mixture of (f) an alkane of from 16 to 24 carbon atoms in amounts ranging from about 10 to 60 grams per mol of said tetrachlorobenzene, distilling the latter mixture to remove therefrom ethylene glycol, and

i. acidifying the residue whereby the phenate present is converted to the corresponding phenol,

6. A process according to claim 3 for preparing 2,4,5- trichlorophenol from l,2,4,5-tetrachlorobenzene by subjecting the latter to hydrolysis utilizing alkaline ethylene glycol, the improvement which comprises:

a. admixing in the absence of a water-entraining agent of from 4 to 8 mols of ethylene glycol with from 2.2 mols to 3 mols of an alkali metal hydroxide,

. heating the mixture to a temperature from to about 210 C., under reduced or atmospheric pressure and removing from the resultant mixture 1 to 2 mols of water thereby forming from 1 to 2 mols of ethylene glycol alkali metal derivative, from 0.2 to 2 mols of free alkali metal hydroxide and from 2 to 7 mols of free ethylene glycol,

c. incorporating into the resultant mixture of (b) above from 0.05 to 0.25 mol of a mono- (lower) 1 to 4 C alkyl benzene or a di- (lower) 1 to 4 C alkyl benzene hydrolysis controlling reagent per mol of tetrachlorobenzene to be hydrolyzed to form a hydrolysis mixture,

d. incorporating 1 mol of 1,2,4,5-tetrachlorobenzene into said hydrolysis mixture,

e. hydrolyzing resultant mixture at reflux temperatures ranging from about to about 200 C.,

f. acidifying the resultant hydrolyzed mixture to a pH of between 11 and 13,

g. incorporating in the so-acidified mixture of (f) an alkane of from 16 to 24 carbon atoms in amounts ranging from about 10 to 60 grants per mol of said tetrachlorobenzene,

h. distilling the latter mixture to remove therefrom ethylene glycol,

i. acidifying the residue whereby the phenate present is converted to the corresponding phenol, and

j. adding to the recovered phenol of from 1 to 5 cc of ammonium hydroxide or ammonia to dehydrate and distill said phenol under vacuum whereby substantially pure phenol is obtained in good yield and purity.

7. A process according to claim 6 in which the hydrolysis controlling reagent is toluene.

8. A process according to claim 6 in which the hydrolysis controlling reagent is xylol.

9. A process according to claim 6 in which the hydrolysis controlling reagent is o-ethyl benzene.

10. A process according to claim 6 in which the hydrolysis controlling reagent is l-ethyl-4-n-propyl benzene. 

2. A process according to claim 1 in which the polyhalobenzene is 1,2,4,5-tetrachlorobenzene.
 3. A process according to claim 1 for preparing 2,4,5-trichlorophenol from 1,2,4,5-tetrachlorobenzene by subjecting the latter to hydrolysis utilizing alkaline ethylene glycol, the improvement which comprises: a. admixing in the absence of a water-entraining agent of from 4 to 8 mols of ethylene glycol with from 2.2 mols to 3 mols of an alkali metal hydroxide, b. heating the mixture to a temperature from 150* to about 210* C., under reduced or atmospheric pressure and removing from the resultant mixture 1 to 2 mols of water thereby forming from 1 to 2 mols of ethylene glycol alkali metal derivative, from 0.2 to 2 mols of free alkali metal hydroxide and from 2 to 7 mols of free ethylene glycol, c. incorporating into the resultant mixture of (b) above from 0.05 to 0.25 mol of a mono- (lower) 1 to 4 C alkyl benzene or a di- (lower) 1 to 4 C alkyl benzene hydrolysis controlling reagent per mol of tetrachlorobenzene to be hydrolyzed to form a hydrolysis mixture, d. incorporating 1 mol of 1,2,4,5-tetrachlorobenzene into said hydrolysis mixture, e. hydrolyzing resultant mixture at reflux temperatures ranging from about 170* to about 200* C., and f. recovering said hydrolyzed tetrachlorobenzene.
 4. A process according to claim 3 for preparing 2,4,5-trichlorophenol from 1,2,4,5-tetrachlorobenzene by subjecting the latter to hydrolysis utilizing alkaline ethylene glycol, the improvement which comprises: a. admixing in the absence of a water-entraining agent of from 4 to 8 mols of ethylene glycol with from 2.2 mols to 3 mols of an alkali metal hydroxide, b. heating the mixture to a temperature from 150* to about 210* C., under reduced or atmospheric pressure and removing from the resultant mixture 1 to 2 mols of water thereby fOrming from 1 to 2 mols of ethylene glycol alkali metal derivative, from 0.2 to 2 mols of free alkali metal hydroxide and from 2 to 7 mols of free ethylene glycol, c. incorporating into the resultant mixture of (b) above from 0.05 to 0.25 mol of a mono- (lower) 1 to 4 C alkyl benzene or a di- (lower) 1 to 4 C alkyl benzene hydrolysis controlling reagent per mol of tetrachlorobenzene to be hydrolyzed to form a hydrolysis mixture, d. incorporating 1 mol of 1,2,4,5-tetrachlorobenzene into said hydrolysis mixture, e. hydrolyzing resultant mixture at reflux temperatures ranging from about 170* to about 200* C., f. acidifying the resultant hydrolyzed mixture to a pH of between 11 and 13, g. incorporating in the so-acidified mixture of (f) an alkane of from 16 to 24 carbon atoms in amounts ranging from about 10 to 60 grams per mol of said tetrachlorobenzene, and h. distilling the latter mixture to remove therefrom ethylene glycol.
 5. A process according to claim 3 for preparing 2,4,5-trichlorophenol from 1,2,4,5-tetrachlorobenzene by subjecting the latter to hydrolysis utilizing alkaline ethylene glycol, the improvement which comprises: a. admixing in the absence of a water-entraining agent of from 4 to 8 mols of ethylene glycol with from 2.2 mols to 3 mols of an alkali metal hydroxide, b. heating the mixture to a temperature from 150* to about 210* C., under reduced or atmospheric pressure and removing from the resultant mixture 1 to 2 mols of water thereby forming from 1 to 2 mols of ethylene glycol alkali metal derivative, from 0.2 to 2 mols of free alkali metal hydroxide and from 2 to 7 mols of free ethylene glycol, c. incorporating into the resultant mixture of (b) above from 0.5 to 0.25 mol of a mono- (lower) 1 to 4 C alkyl benzene or a di- (lower) 1 to 4 C alkyl benzene hydrolysis controlling reagent per mol of tetrachlorobenzene to be hydrolyzed to form a hydrolysis mixture, d. incorporating one mol of 1,2,4,5-tetrachlorobenzene into said hydrolysis mixture, e. hydrolyzing resultant mixture at reflux temperatures ranging from about 170* to about 200* C., f. acidifying the resultant hydrolyzed mixture to a pH of between 11 and 13, g. incorporating in the so-acidified mixture of (f) an alkane of from 16 to 24 carbon atoms in amounts ranging from about 10 to 60 grams per mol of said tetrachlorobenzene, h. distilling the latter mixture to remove therefrom ethylene glycol, and i. acidifying the residue whereby the phenate present is converted to the corresponding phenol.
 6. A process according to claim 3 for preparing 2,4,5-trichlorophenol from 1,2,4,5-tetrachlorobenzene by subjecting the latter to hydrolysis utilizing alkaline ethylene glycol, the improvement which comprises: a. admixing in the absence of a water-entraining agent of from 4 to 8 mols of ethylene glycol with from 2.2 mols to 3 mols of an alkali metal hydroxide, b. heating the mixture to a temperature from 150* to about 210* C., under reduced or atmospheric pressure and removing from the resultant mixture 1 to 2 mols of water thereby forming from 1 to 2 mols of ethylene glycol alkali metal derivative, from 0.2 to 2 mols of free alkali metal hydroxide and from 2 to 7 mols of free ethylene glycol, c. incorporating into the resultant mixture of (b) above from 0.05 to 0.25 mol of a mono- (lower) 1 to 4 C alkyl benzene or a di- (lower) 1 to 4 C alkyl benzene hydrolysis controlling reagent per mol of tetrachlorobenzene to be hydrolyzeD to form a hydrolysis mixture, d. incorporating 1 mol of 1,2,4,5-tetrachlorobenzene into said hydrolysis mixture, e. hydrolyzing resultant mixture at reflux temperatures ranging from about 170* to about 200* C., f. acidifying the resultant hydrolyzed mixture to a pH of between 11 and 13, g. incorporating in the so-acidified mixture of (f) an alkane of from 16 to 24 carbon atoms in amounts ranging from about 10 to 60 grams per mol of said tetrachlorobenzene, h. distilling the latter mixture to remove therefrom ethylene glycol, i. acidifying the residue whereby the phenate present is converted to the corresponding phenol, and j. adding to the recovered phenol of from 1 to 5 cc of ammonium hydroxide or ammonia to dehydrate and distill said phenol under vacuum whereby substantially pure phenol is obtained in good yield and purity.
 7. A process according to claim 6 in which the hydrolysis controlling reagent is toluene.
 8. A process according to claim 6 in which the hydrolysis controlling reagent is xylol.
 9. A process according to claim 6 in which the hydrolysis controlling reagent is o-ethyl benzene.
 10. A process according to claim 6 in which the hydrolysis controlling reagent is 1-ethyl-4-n-propyl benzene. 